Goal:
    A : Type  P : list A → A → Type  b0 : All_fold P []  b' : list A
  ============================
   (∀ b : All_fold P b',
      {| pr1 := []; pr2 := b0 |} = {| pr1 := b'; pr2 := b |}
      → let H := CoreTactics.block in
        NoConfusionHom_All_fold A P [] (All_fold_nil P) b0
        → let H0 := CoreTactics.block in All_fold_nil P = b0)


DEBUG:Going to execute:
intros p